Develop a Business App Using SAP Business Application Studio

1. In the db folder, create a new file called schema.cds.

2. Populate the file with the following entity definitions:

   using { Currency, managed, sap } from '@sap/cds/common';
   namespace my.bookshop;
   
   entity Books : managed {
     key ID : Integer;
     title  : localized String(111);
     descr  : localized String(1111);
     author : Association to Authors;
     genre  : Association to Genres;
     stock  : Integer;
     price  : Decimal(9,2);
     currency : Currency;
   }
   
   entity Authors : managed {
     key ID : Integer;
     name   : String(111);
     books  : Association to many Books on books.author = $self;
   }
   
   /** Hierarchically organized Code List for Genres */
   entity Genres : sap.common.CodeList {
     key ID   : Integer;
     parent   : Association to Genres;
     children : Composition of many Genres on children.parent = $self;
   }
   
   

3. Save your changes.

   The schema.cds file is shown with an error. That’s expected and will be resolved in the next section.

1. In the srv folder, create a new file called cat-service.cds.

2. Populate the file with the following service definitions:

   using { my.bookshop as my } from '../db/schema';
   service CatalogService @(path:'/browse') {
   
     @readonly entity Books as SELECT from my.Books {*,
       author.name as author
       } excluding { createdBy, modifiedBy };
   
       action submitOrder (book : Books.ID, amount: Integer);
     }
   
   

3. Save your changes.

1. In the db folder, create a new folder called data.

2. In the data folder, create a new file called my.bookshop-Authors.csv, and populate it with the following:

   ID;name
   101;Emily Brontë
   107;Charlotte Brontë
   150;Edgar Allen Poe
   170;Richard Carpenter
   

3. In the data folder, create a new file called my.bookshop-Books.csv, and populate it with the following:

   ID;title;author_ID;stock
   201;Wuthering Heights;101;12
   207;Jane Eyre;107;11
   251;The Raven;150;333
   252;Eleonora;150;555
   271;Catweazle;170;22
   
   

4. Save your changes.

In the srv folder, create a new file called cat-service.js, and populate it with the following:

/**
* Implementation for CatalogService defined in ./cat-service.cds
*/
const cds = require('@sap/cds')
module.exports = function (){
  // Register your event handlers in here, e.g....
  this.after ('READ','Books', each => {
    if (each.stock > 111) {
      each.title += ` -- 11% discount!`
    }
  })
}

Your application should look similar to the structure shown in the picture below.

Save your changes.

You can also see the semantic structure of the application by expanding the CAP Project explorer located at the bottom of the EXPLORER view.

You can explicitly deploy your application to a persistent local SQLite database, or you can run your application and it will implicitly use an in-memory database.

This step describes how to run the application with an in-memory database.

You will first add all required dependencies, and the create and run a run configuration.

1. Add and install all required dependencies.

   • From the Terminal menu, select New Terminal.

   • On the bookshop folder, run the following:

     npm install
     
     

2. From the left side menu, open the Run Configurations view.

   

3. Click + at the top of the view to add a new configuration.

   

4. Select bookshop as the runnable application from the command palette prompt.

   There might be other run configuration options available in the command palette.

   

5. Press Enter to use the default name for the configuration. A new configuration is added to the run configuration tree.

6. Click the right green arrow on the right of the configuration name to run the application.

   

7. When prompted, click Expose and Open for port 4004.

   

   The port 4004 the application is running on is exposed to external access, in this case, to the browser.

8. Press Enter to use the default description. The application opens in the browser and you can click to see the metadata and entities the service.

   

   You can also debug your application to check your code logic. For example, to debug the custom logic for this application, perform the following steps:

9. Place a breakpoint in the function in the cat-service.js file.

10. In the running app, click the Books entity. It should stop at the breakpoint.

    

11. Click Debugger icon on the side menu to open the Debugger view. Click Continue in the debugger until all the books are read and the page is presented.

    Remove the breakpoint.

12. Stop the application by clicking Stop in the Debug pane. The number beside the Debug icon represents the number of running processes. Click Stop until there are no processes running.